The prior art comprises cells that are designed for cleaning surfaces by means of pickling acid activated by electropolishing action characterized in that the metal surface to be cleaned, pickled and/or polished is treated continuously by the electropolishing action with a limited quantity of the pickling acid between the electrode and the surface; the pickling acid usually flows in and out from the cell.
European patent application EP 0 289 168 A1, to Turner et al., teaches an electroplated polishing device comprising a cell with deformable O-ring seal around its peripheral edge and ducts to let the acid flow in and out; furthermore around the edge another O-ring seal is provided to define a circular cross-section between seals connected to a vacuum pump so that the vacuum can be applied between seals for preventing the escape of pickling acid from the cell.
Furthermore, a similar prior-art device known for many years old not find practical application because of the difficulty in using the cell by hand operation, because of the impossibility of defining the working environment of the electrochemical agent without applying the vacuum or seals around the cell.
In addition, the prior art includes U.S. Pat. No. 5,135,632, to Weber, which teaches an apparatus for electropolishing surfaces comprising a circulating pump for providing the electrolyte to the surface to be treated; a cell being closed on all sides except for a side oriented towards the surface to be electropolished with an electrode for performing electropolishing; a peripheral seal attached to the rim of the inner housing (i.e., cell); an outer housing, with a peripheral seal attached to the rim of the outer housing, is provided for aspirating the rinsing fluid with a different closed circuit from the electrolyte closed circuit; the two closed circuits have relevant tank and recirculating pump each.
However, the aforementioned cell with the outer housing performs the electrpolishing with two different circuits, one for the pickling acid and the other for the rinsing fluid; the two fluids are not mixed and each of them have separation from aspirated air into its tank; thus these cell is not very useful for applying electropolishing by hand, since it is very heavy and complicated.
Moreover, the prior-art includes U.S. Pat. No. 3,443,991, to Kremm, which uses a scrubber system in a pickling process to abate the pollution of air and water and eliminate waste disposal problems; this aim is obtained by treating an hydrochloric acid solution and iron chloride by continuously reconditioning the used solution acid and regeneration of the acid solution. Kremm further teaches a scrubber having a mist remover to pick up acid and water vapours of the pickling tank. However, the liquid solution has a different circuit from the circuit of the fumes, acid, water vapour and entrained moisture particles; two scrubbers are provided one to treat the fumes, acid and water vapour and entrained moisture particles, and the other with the mist remover to treat the gases from first scrubber; the process works by exchanging warm and cool from the fluids and has exchangers for heat dissipation.
Finally, the prior-art includes the manual method of chemical cleaning the metal surfaces with pickling agents in the form of concentrated liquid acid or gel which are manually placed by the operator on the cleaning area and are left for a period of time ranging from a few minutes to several hours for the reaction to take place and then are washed off so that the entire agent is lost by being washed through the drainage point so that the workplace has to be equipped with waste-water treatment systems to prevent pollution of the external environment.